Christians across America are being called upon to unite in prayer and fasting for the nation from Sept. 20 to Oct. 30 as America faces “unprecedented challenges.”

“We call on all faithful Christians to join us in the fight to defend life, protect and revitalize marriage, and preserve religious liberty and the rights of conscience,” says Jim Garlow, pastor of Skyline Wesleyan Church in San Diego, who is spearheading the prayer effort.

“We must work tirelessly in all the ‘seven spheres of cultural influence,’” he adds, referring to the home; the church; civil government, law, and military; business and technology; education; media; and arts, entertainment and professional sports.

While the prayer and fast official begin at 7:14 a.m. ET on Sept. 20 (based on 2 Chronicles 7:14), organizers of the effort have scheduled three webcasts before the kick-off to prepare participants for the 40-day effort.

The first of the three is scheduled for Sept. 4, and will take place 9 a.m. to 9 p.m. PT live from Sacramento, Calif. The second and third will take place from Washington, D.C., at 8 p.m. ET.

A fourth webcast has also been scheduled but will take place after the conclusion of the 40-day period – on Oct. 30 at 6 p.m. ET. The fast will officially conclude at 7:14 a.m. ET on Oct. 30.

In addition to praying, participants of the “Pray & A.C.T.” effort are being encouraged to “Affirm the Basics” by signing the Manhattan Declaration, a statement that affirms the sanctity of life, sacredness of marriage, and the preservation of religious liberty – three foundational principles that organizers say are facing “unprecedented challenges.” Since its unveiling last November, the declaration has been signed by over 470,000 individuals.

Participants are also being encouraged to “Conform” their lives to their talk by engaging in compassionate acts during the 40-day effort and beyond.

Furthermore, participants are being encouraged to “Transform the culture” by working for the restoration of values. This includes “speaking up winsomely” for the three foundational principles and consistently voting in all elections for candidates who affirm the principles.

Notably, the 40-day effort comes ahead of this November's midterm elections and has drawn the support of conservative leaders including Jim Daly of Focus on the Family; Maggie Gallagher of the National Organization for Marriage; Bishop Harry Jackson, Jr., of the High Impact Leadership Coalition; Richard Land of the Ethics and Religious Liberty Commission; Tony Perkins of the Family Research Council; Penny Nance of Concerned Women for America; and Tim Wildmon of the American Family Association.

Other notable Christian leaders who have endorsed the effort are Vonette Bright of Campus Crusade for Christ International; Lou Engle of TheCall; Jack Hayford of The King's College and Seminary; Ron Luce of Teen Mania; and Samuel Rodriguez of the National Hispanic Christian Leadership Conference.